Earlier insights Children who develop autism already show signs of different brain responses in their first year of life, say scientists in a study that may in the future help doctors diagnose the disorder earlier.

The team of researchers, which included Dr Kristelle Hudry of LaTrobe University in Melbourne, studied 104 babies at 6 to 10 months and then again at 3 years. They found that those who went on to develop autism had unusual patterns of brain activity in response to eye contact with another person.

The findings, published in the journal Current Biology, suggest direct brain measures might help predict the future risk of autism in babies as young as 6 months old, says Mark Johnson of Birkbeck at the University of London, who led the study.

Autism, which affects around 1 per cent of people worldwide, includes a spectrum of conditions ranging from mental retardation and a profound inability to communicate to relatively milder symptoms such as seen in people with Asperger's syndrome.

Among core features of condition are poor communication skills and difficulties with social engagement, and doctors are keen to find ways to diagnose the condition earlier so that they can intervene to help autistic children develop coping skills.

Characteristic autistic behaviour tends not to emerge before the age of 2 years and firm diagnoses are usually only made after this age.

"Because there are no good behavioural signs at this young age (under 1 year), we wanted to see whether, by measuring the activity of the brain in a more direct way, we might be able to pick up earlier warning signs," says Johnson.

His team looked at babies at greater risk of developing autism later in life because they had an older brother or sister with the condition.

Reacting to faces

The researchers used passive sensors placed on the scalp to register brain activity while the babies viewed faces that switched from looking at them to looking away.

The babies who were later found to be typically developing children showed a clear difference in brain activity in response to a face looking towards them compared to a face looking away.

In contrast, most of the babies who later went on to develop autism symptoms showed much less of a difference in brain activity when someone made eye contact and then looked away.

The researchers cautioned however that the predictive markers were not 100 per cent accurate, as the study did find cases of babies who showed no differences in brain function and were not later diagnosed, and vice versa.

Johnson says the results are a first step towards earlier autism diagnosis, but adds that more research was needed to confirm and strengthen the brain activity markers.